American astrochemist Raymond Davis, Jr. was the first scientist to collect neutrinos — tiny, elusive particles emitted from the nuclear-fusion reactions in the core of the Sun, and his work showed that the Sun's heat and fury is caused by the fusion of four protons into helium-4. In 1968 he discovered the solar-neutrino anomaly, wherein the Sun generates energy by nuclear fusion of hydrogen into helium, creating electron-type neutrinos that are changed into other types of neutrinos during their journey from the Sun to the Earth. Davis conducted decades of experiments deep in the Homestake Gold Mine in the Black Hills of South Dakota, where the darkness and distance underground helped shield the neutrino detector from ordinary cosmic rays, which would otherwise obscure any signals caused by neutrino collisions. He shared the 2002 Nobel Prize for Physics with Masatoshi Koshiba, whose work confirmed Davis's findings.